Occlusion device

ABSTRACT

An obturator for a bronchial tube or tubule of a human or animal lung comprises a blocking element ( 92 ) and a securing element ( 90 ). The blocking element serves to seal the tube or tubule against the passage of fluid past the obturator when the obturator is disposed in a bronchial tube or tubule. The securing element serves to retain the blocking element in position. The blocking element comprises a substantially cylindrical plug of biocompatible, resiliently deformable closed-cell foamed plastics material, such as PVC. The securing element comprises a stent having barbs ( 98 ) to engage and retain the blocking element. The stent also has anchors ( 100 ) to retain the stent in a bronchial tube or tubule. A method of treatment of emphysema or other lung conditions or diseases in human or animal patients comprises placing an obturator in a bronchial tube or tubule of the patient so as to seal the tube or tubule against the passage of fluid past the obturator.

This application is a continuation of co-pending U.S. patent applicationSer. No. 09/762,692, entitled “Occlusion Device”, filed Oct. 31, 2005,which is the National Stage of International PCT Application No.PCT/GB98/00652, entitled “Occlusion Device”, filed Mar. 3, 1998, whichclaims the benefit of priority to U.K. Patent Application No. 9708681.3,entitled “Lung Treatment Device”, filed Apr. 30, 1997. Disclosures ofthe aforementioned patent applications are hereby incorporated byreference in their entirety.

SUMMARY

The present invention relates to a device useful in the treatment ofemphysema and other diseases or disorders of the human or animal lung.

Emphysema is a disease of the lung caused primarily by prolongedsmoking, although not exclusively thereby. It is an unrelentless,intractable and debilitating process. Emphysema is defined as anabnormal permanent enlargement of the air spaces distal to the terminalbronchioles, accompanied by destruction of their walls without obviousfibrosis. In this context, destruction means non-uniformity in thepattern of respiratory,airspace enlargement; orderly appearance of theacinus is disturbed and may be lost.

Emphysema causes a physiological loss of lung elastic recoil, whichdecreases expiratory airflow by loss of driving pressure and prematureairway closure from reduced airway traction. The effect of this is thatthe alveoli become hyper-inflated without there being any real exchangeof air with the outside. Therefore the patient begins to feel starved ofoxygen and so attempts to breathe more deeply. In breathing more deeply,the effects are exacerbated.

Not only are those individual alveoli which have a block in theirrespective bronchial tubules affected, but also neighbouring alveoli,perhaps in other regions of the lung, which may otherwise be perfectlyserviceable, become affected because the hyper-inflated alveolipressurise neighbouring alveoli and prevent them from expanding fully.There is, of course, a relatively fixed “exchange” volume of anindividual's lung, that is to say, the difference between the expandedvolume and the deflated volume. Emphysema reduces the exchange volumebecause undeflated alveoli occupy that space. Consequently, the onlyrecourse available to the patient is to increase the expanded volume,thereby resulting in the barrel chest symptomatic of emphysemasufferers.

The major therapeutic modalities currently available consist ofbronchodilator and anti-inflammatory drugs, directed at decreasingairway resistance, and antibiotics to treat acute and chronic infection.Supplemental oxygen therapy for the hypoxaemic patient improves exerciseperformance and improves survival in patients with cor pulmonale.Despite all available medical therapies, the course of the disease isone of progressive limitation, increasing dyspnoea and significantincrease in overall mortality.

It has long been realised that full lung volume is more than enough forsurvival in most circumstances and that a person can survive quitesatisfactorily with only one lung, for example. Heterogenousdistribution of emphysema, together with the lack of pulmonary bloodflow to those areas have made lung volume reduction surgery a logicaloption. Removal of parts of the lung affected by emphysema permitsunaffected areas to become operative again and so enable a betterquality of life for the patient. Clearly, however, such invasiveprocedures are of a very serious nature and some patients will not, inany event, be in a sufficiently strong condition to accept the trauma ofsuch procedures. Primarily, the basic relief for emphysema sufferers isinactivity, on the one hand, and breathing pure oxygen, on the other.

Emphysema is a distressing condition affecting a relatively largeproportion of the population, and a more effective and less traumatictreatment is required.

On a different matter, other lung conditions sometimes lead to bleedinginto the lung. A patient having this condition feels movement of theblood caused by airflow in the lung during breathing, and perceives theblood as a foreign body and irritant. The patient coughs in an attemptto dislodge the perceived foreign body. Coughing blood, of course, issometimes the first warning of a more serious disease or condition, butonce that is realised, there is no benefit in such bleeding. Moreover,in such conditions where the lung might heal itself and subsequentlystop bleeding, or indeed simply where the bleeding needs to be confined,the coughing reaction, which is almost impossible to resist, does nothelp the situation at all, and merely spreads the blood to other areasof the lung.

U.S. Pat. No. 5,382,261 discloses a vessel occluder for providingpermanent occlusion of a vessel in a person by use of a flexible closuremember attached to at least one radially expandable stent. The occluderdoes not have barbs or anchors or a stent.

DE-U-9205797 discloses a self expanding ‘meshbasket’ for the occlusionof human hollow organs. The invention is directed to femalecontraceptive devices and addresses the problem of remaining in place.The device may also find application in embolism therapy and vascularocclusion.

WO-A-9532018 discloses a body passageway closure for use in theocclusion of various passageways within the body, with particularapplication for the occlusion of blood vessels.

Therefore it is an object of the present invention to provide a methodof treatment of certain lung conditions or diseases and to provide adevice for such treatment.

In accordance with a first aspect of the present invention there isprovided a method of treatment of emphysema or other lung conditions ordiseases, the method comprising placing an obturator in a bronchial tubeor tubule so as to seal the tube or tubule against the passage of fluidpast the obturator.

In the case of emphysema, and by the simple expedient of inserting anobturator in a bronchial tube, a section of a lung can be isolated sothat no air can be drawn into it. Thereafter, the isolated part deflatesin time as the air remaining in it becomes absorbed, and so that part ofthe lung stops affecting other areas of the lungs, which can thusperform normally. Such a procedure is relatively simple, requiring onlya delivery device for the obturator, which device is inserted throughthe mouth and airway of the patient until the proposed placement site isreached, whereupon the device is activated to release the obturator fromthe device.

In the case of bleeding into the lung, an obturator stops the flow ofblood. The lung is tamponated by the obturator and blood merely collectsin the isolated part of the lung and ultimately, if the bleeding stops,will be reabsorbed. Alternatively, in the case of some, perhapsterminal, conditions such as some lung cancers, it at least providestemporary relief for the patient.

In accordance with a second aspect of the invention there is providedthe use of a blocking element and a securing element in the manufactureof an obturator for use in the treatment of a lung condition in a humanor animal by blocking a bronchial tube or tubule. The condition may beemphysema.

Preferably the two elements are separate components, the blockingelement serving to seal the tube or tubule against the passage of fluidpast the obturator when the obturator is disposed in a bronchial tube ortubule, and the securing element serving to retain the blocking elementin position in the tube or tubule.

The blocking element preferably comprises a substantially cylindricalplug of biocompatible material. The plug may comprise resilientlydeformable closed-cell foamed plastics material, such as PVC, so that itmay be compressed to facilitate insertion into the tube or tubule andthereafter expand to fill the cross-section of the tube or tubule.

It is known to employ stents in medical fields to expand and supportcollapsed blood vessels, and indeed bronchial tubes. A stent is acompressible framework which, when inserted into a vessel and released,expands and, within the limits of its expansion, supports and possiblyexpands the walls of the vessel.

Preferably, the securing element comprises a stent. The stent may havebarbs to engage and retain the blocking element. The stent preferablyalso has anchors to retain the stent in a bronchial tube or tubule.

In one embodiment, the stent comprises a crown of surgical quality steelwire legs in zig-zag formation. Said barbs and anchors may depend frompoints of the crown. Preferably the crown is closed in itscircumference, although this is not essential.

In another embodiment, the stent comprises a dome of surgical qualitysteel wire legs. Said barbs and anchors may be formed on the ends ofsaid legs.

It is known in medical fields to block blood vessels, for example wherea genetic or other defect has resulted in a hole which needs blocking,or, for example, in the case of babies whose aortic to pulmonary arteryconnection has not closed following birth, a condition known as patentductus arteriosus. In the case of holes, it is well known to employ an“umbrella”, where a diaphragm of material forms the seal against theblood vessel wall, the handle of the umbrella serving to keep thediaphragm across the vessel. In the case of babies, it has also beenknown to employ a plug of PVC foam to treat patent ductus arteriosus,the plug encouraging clotting.

However, in the case of bronchial tubes and tubules a diaphragm seal hasnot been used yet, although its application cannot be entirely ruledout. For example, an umbrella device with a larger surface area ofcontact with the bronchial mucosa might be as effective.

In blood vessels a complete seal is seldom required because any leaksoon blocks by the formation of a clot; something that would not happenin an airway of a lung. Secondly, airways are not always absolutelycircular in section, so a circular diaphragm may not always make a goodseal, at least around some parts of the circumference, unless it hascapacity to expand in all radial directions and has a large contactarea.

However, a complete seal is an absolute requirement of the presentinvention (at least over the period of a single breath), because withoutit, air can leak past during inhalation and pressurise the lung in justthe same way, and perhaps even to a greater extent. More importantly,however, a patient with such an obturator in place can only feel itspresence if there is movement of air around it to stimulate adjacentnerve endings. Once a patient can feel the obturator, there will beirresistible compulsion to cough which, if done excessively, may besufficient to dislodge the obturator.

Thus it has been found that a very effective seal is achieved by the useof said cylindrical plug of foamed PVC (of the type commonly employed asearplugs). The effectiveness of this arrangement is probably due to thefact that any leakage path has to be a long one and there are thusnumerous opportunities for it to close and seal about at least oneclosed circuit around the plug. Another reason is that a plug can moulditself to the shape of the tube or tubule, which is itself unlikely tobe cylindrical, or, indeed, circular in cross-section.

Preferably, the method of the present invention employs an obturator ofthe type defined above.

The delivery device preferably comprises a delivery tube in which theobturator is received in a compressed state at a distal end thereof, aguide tube, which is capable of following a possibly tortuous path underthe guidance of a surgeon from entry into the mouth of a patient, downthe patient's trachea and one bronchus to a proposed delivery site in abronchial tube or tubule, and which has a passage to receive thedelivery tube therealong, and release means to eject the obturator fromthe delivery tube and guide tube.

The obturator needs to slide in the delivery tube during ejection andthe stent provides a low friction surface of the obturator to facilitatesuch ejection.

It is feasible that the blocking and securing elements may be integrallyformed from plastics material, and wherein the securing elementcomprises adhered or fused anchor elements on the blocking element.

It is also feasible that the securing element may comprise a memorymetal which is released to its normal expanded shape by a physicalparameter, for example, the passage of an electric current therethrough,once it has been inserted at the proposed location. Otherwise it is inthe same form as the above described steel stent which relies onresilience for its expansion. The advantage of a memory metal device isthat it requires no compression during insertion so that the deliverytube of the delivery device may be replaced by a simple guide rod towhich it is connected.

DESCRIPTION OF DRAWINGS

The invention will be better understood from the following descriptionof particular embodiments given as non-limiting examples. Thedescription refers to the accompanying drawings, in which:

FIG. 1 shows a section through the human chest indicating the locationof bronchial obturators in the lungs;

FIG. 2 shows a bronchial obturator complete with delivery system;

FIGS. 3 a b and c show in perspective two embodiments of an obturatoraccording to the present invention, that of FIG. 3 a having a crownstent, and that of FIG. 3 b having a dome stent, FIG. 3 c being a crownstent in an open configuration prior to rolling and, optionally, weldinginto a ring as in FIG. 3 a;

FIGS. 4 a and b show an internal barb and external anchor respectively;

FIG. 5 is a perspective view of another embodiment of obturator inaccordance with the present invention; and,

FIG. 6 is a perspective view of yet another embodiment of obturator alsoin accordance with the present invention.

DETAILED DESCRIPTION

In FIG. 1 of the drawings, a human chest cavity 10 includes a pair oflungs 12 which each comprise upper and lower lobes 14,16. A trachea 18branches into two bronchi 20, which further branch into bronchial tubes22 and segmental bronchi 24. The bronchi 24, after further branching,terminate in alveoli 26.

In the majority of patients suffering from emphysema, it frequentlyeffects mainly the upper lobes 14 of the lungs, leaving the lower lobes16 unaffected, or at least less affected. However, if no treatment isgiven to a patient, the expansion effect of the upper lobes as thecondition develops presses on the lower lobes and reduces their capacityto perform efficiently. Lower lobe emphysema does occur in somepatients, and in which event it is then the upper lobes which arecompressed.

Thus the present invention suggests placing an obturator 50 in abronchial tube or tubule to isolate the region of the lung supplied bythat tube or tubule. Where the obturator is placed will be decided bythe surgeon and will depend on the how localised the damaged region oflung is. That is to say, if the whole lobe is badly affected, then theobturator is placed in the lobar bronchus 22 supplying that lobe (asshown at 50 in FIG. 1). On the other hand, if the damage is morelocalised, then the obturator will be placed in a smaller segmentalbronchus 24, (as shown at 50′ in FIG. 1). Thus more than one obturatormay be employed in the same pair of lungs isolating different regions ofthem. They will also be of different sizes, depending where they are tobe inserted.

The above considerations equally apply when the condition being treatedis not emphysema but some other condition which a doctor considers canusefully be treated by the method of the present invention. Such anothercondition is where a lung, or part of it is bleeding into the airway andan obturator isolates the bleeding region and inhibits coughing whichmay damage the lung further, or at least cause further discomfort to thepatient.

FIG. 2 shows an endo-bronchial obturator 50 complete with deliverydevice 70. The delivery device comprises a handle 72 and flexible guidetube 74. Slidably received in the guide tube is a delivery tube 76having the obturator 50 disposed at its distal end 78. A release means80 is insertable in a proximal end 82 of the delivery tube 76 and bymeans of which the obturator 50 may be ejected from the end of thedelivery tube. The guide tube is guided down the trachea and into theappropriate bronchus by means of guide lines (not shown) which enablethe delivery system to be turned to follow the desired course. Opticalguidance means may be included, or real-time X-ray or other monitoringmethods may be employed to guide the surgeon. Once the end of the guidetube reaches the correct location, the delivery tube is inserted in thehandle end of the delivery device 70, and then the release means 80 ispushed down the tube 76 to eject the obturator. The obturator is adaptedto expand or be expanded, when ejected, to fill and block the tube ortubule in which it is inserted.

As can be seen from FIG. 3 a, the obturator 50 a in its first embodimentis comprised of two main components, a securing element in the form of astent 90, and a blocking element in the form of a closed-cell, PVC foamplug 92.

The stent 90 is constructed from a plurality of legs 91 of surgicalgrade stainless steel wire welded together such that when extended thestent appears as a series 90 b of connected ‘W’s, as shown in anunconnected disposition in FIG. 3 c. Indeed, it is not essential thatthe final connection between ends 94,96 be made to form a closed crownarrangement (as shown in FIG. 3 a); it is equally effective merely toroll the stent 90 b as indicated by arrows in FIG. 3 c.

When the two ends of the stent are joined together, the stent 90 foldsinto a circular frame or crown, capable of encompassing thebiocompatible block 92. The stent is constructed so as to be of a sizeslightly smaller (in its unstressed condition) than the block, so thatits natural resilience squeezes the block slightly. On the other hand,the stent should be larger than the airway into which it is to beintroduced so that it presses outwardly against the wall of the airway,and is incorporated into the mucosa of the air passage.

The legs 91 of the stent crown are fitted with both internal barbs 98and external anchors 100. The barbs 98 embed themselves in the block 92and secure the block to the stent 90. The anchors 100 are adapted toengage the walls of the patient's airways to hold the stent in position.

FIG. 4 a shows an internal barb 98. The internal barb, also constructedfrom surgical quality stainless steel, is substantially straight and hasa hook 99 at one end. The hooked end 99 is the point and means by whichthe barb is secured to the biocompatible block.

FIG. 4 b shows an external anchor 100. The anchor, which is alsoconstructed from surgical quality stainless steel, is againsubstantially straight and has a coil 101 at its end. A coil is used sothat damage is not caused to the tissue of the airway in which theobturator is fitted, particularly if and when the obturator is removed.

The barbs and anchors are joined to the stent crown by a welded jointbetween two adjacent legs 91. Barbs can alternate with anchors at thesame end of the stent, or one end can have all barbs, while the otherend has all anchors. Both arrangements are shown in FIGS. 3 a and crespectively.

A different embodiment of obturator 50 b, also in accordance with thepresent invention, is shown in FIG. 3 b in which surgical qualitystainless steel wires are all welded together at a point 104 to form adomed stent 90 b. Legs 91 b are alternately turned inwards to form barbs98 b, or outwards to form anchors 100 b. Alternatively, all the legscould be anchors 100 b, with interspersed shorter barbs 98 bb, as one isshown in dashed lines in FIG. 3 b.

The aforementioned obturators all rely on resilience of the steel toreturn the stent to its original shape once released from the deliverymechanism and so as to enable fitment in a narrower tubule than theunstressed size of the stent would otherwise allow. However, thisrequires prestressing the stent and keeping it stressed during delivery.Thus the present invention may find suitable application for memorymetals, which only return to their original shape when some physicalcondition changes, for example, temperature rise or electrical currentflow.

It is essential for the blocking device 92 to be comprised of aresiliently deformable material such as PVC foam as mentioned above.This enables the blocking device to be easily surrounded by the stent 90and deformed into a compact structure, thereby enabling delivery of theblock to its destination in the lung.

It is likewise essential that the block be capable of expanding andreforming into its original shape once deposited in the desired locationin the lungs. It should be noted that the block is deformed and reformedin both an axial and a radial direction. It is the block 92 which sealsa bronchial tube or tubule; mucous surrounds the block and forms a fluidtight seal. The presence of the stent around the block does not inhibitsealing in any way since the stent is essentially incorporated into themucosa lining the airway.

Under compression, PVC foam has a high coefficient of friction whichwould prevent ejection from the delivery device as described above, ifit was not surrounded by the stent 90, which offers a relatively lowfriction surface to the inside of delivery tube 76.

However, it is feasible that the block 92 could include a low frictionsurface to enable such ejection without the stent. Instead of the stentas described above, anchor means might be moulded in biocompatibleplastics material as a crown, for example, on one end of the block, andeither be adhered, fused or otherwise bound thereto.

The effectiveness of the device depends, to some extent, on the lengthof the block. Moreover, the block is required to be of a size which isboth comfortable to the patient once expanded in the lung and whichexpands to completely obstruct the passage of air into the affectedportions of the lung. The extended size of the block therefore rangesbetween 5 mm and 25 mm in length, and between 5 and 11 mm in diameter,depending on the size of the tube or tubule to be obturated.

Obturator 50 c shown in FIG. 5, comprises a balloon 200, which isinflated after insertion and then detached. The balloon is captivated inan appropriate securing device such as stent 202. In this case, thebarbs would not be sharp, but would merely retain ends of the balloon,or, as shown, would comprise turned-in points 204,206 at each end of thestent. Anchors 201 are provided.

Finally, as mentioned above, the obturator may be as shown at 50 d inFIG. 6, where it comprises a diaphragm 300 expanded by an internal stent302 having anchors 302. One end 306 of the diaphragm is attached to thestent to retain it on the stent. The diaphragm is also adhered to thestent.

While the obturator and method of the present invention has beendescribed with reference to human patients, animal patients may incertain circumstances also benefit.

1. A method of treating a lung, comprising: providing a flow controldevice, the flow control device comprising a frame adapted toself-expand from a contracted configuration to an expandedconfiguration, the frame coupled to a membrane; inserting the flowcontrol device in a bronchial passageway such that the frameself-expands within the bronchial passageway and the membrane seals witha wall of the bronchial passageway so that the flow control elementprohibits air from flowing past the flow control element in aninhalation direction within the bronchial passageway and also prohibitsair from flowing past the flow control element in an exhalationdirection within the bronchial passageway.
 2. A method as in claim 1,wherein the flow control device has a proximal end and a distal end, andwherein a transverse dimension of the flow control device is greatest ata location in between the proximal end and the distal end.
 3. A methodas in claim 1, wherein the flow control device has a proximal end and adistal end, and wherein a diameter of the flow control device at alocation between the proximal and distal ends is greater than thediameters at the proximal end and at the distal end.
 4. A method as inclaim 1, wherein the flow control device has a largest diameter at alocation between proximal and distal ends of the flow control device. 5.A method as in claim 1, wherein a diameter of the flow control deviceundergoes an increase moving from a distal end of the flow controldevice toward a proximal end of the flow control device, and wherein thediameter also undergoes a decrease moving from the distal end toward theproximal end.
 6. The method of claim 1, wherein the membrane forms anair tight seal with a wall of the bronchial passageway.
 7. The method ofclaim 1, wherein the flow control device self-expands in a manner suchthe flow control device has an enlarged diameter at a location betweenproximal and distal ends of the flow control device.
 8. The method ofclaim 1, wherein the frame includes at least one anchor and wherein theat least one anchor attaches to the wall of the bronchial passageway. 9.The method of claim 1, further comprising: inserting a delivery tubeinto the bronchial passageway, the delivery tube loaded with the flowcontrol device; and guiding the delivery tube to a location within thebronchial passageway prior to releasing the flow control element.